Investigation sequence
Classify the event timing
Separate no-motor instant trip, load-only trip and repaired-channel trip; each points to a different boundary.
Compare driver rails
Check positive drive, negative off-bias and reference points across all six channels; the protection path depends on correct bias.
Verify PWM-to-gate chain
Trace command through optocoupler isolation and push-pull amplification before condemning the module.
Interpret VCE action
A high collector-emitter voltage during a commanded-on pulse can mean true overcurrent or weak drive; the action itself may be correct.
Record the protection feedback
Close the record with whether GF/OC feedback originated from module stress, driver weakness or a protection-component fault.
Stop conditions
- Negative gate bias absent
- Driver output cannot source/sink gate current
- VCE detection path modified
- Module shows leakage
- Field output path still suspect
Linked records
The useful diagnostic question is whether the fast protection circuit detected a true output event or whether the gate driver itself failed to turn the module on hard enough. The page maps PWM isolation, push-pull gate current, negative bias and VCE detection into one repair route.
Turns the 616G3 discrete driver/protection explanation into a public diagnostic route: PWM isolation, push-pull amplification, negative gate bias, VCE rise detection and GF/OC feedback to the CPU.